# coding=utf-8
def main():
	fp = open("03.txt", "r")
	data = fp.read()
	import re
	pattern = re.compile('[^A-Z][A-Z]{3}([a-z])[A-Z]{3}[^A-Z]')
	m = pattern.findall(data)
	print "".join(m)
	# 打印：linkedlist
	# 下一关：http://www.pythonchallenge.com/pc/def/linkedlist.html
	# 显示内容：linkedlist.php
	# 更改网址变为：http://www.pythonchallenge.com/pc/def/linkedlist.php

if __name__ == '__main__':
	main()
